Wireless equipment usually undergoes many kinds of tests in order to ensure sufficient performance. Some tests are mandated by standards, while others are performed as part of product development and verification. A particular class of tests is that where the over-the-air performance of the communication between one or several wireless transmitter and receivers is tested. The purpose of such a test could be to ensure that handsets are adequately designed and work well in the presence of a human being, which is important for operators when determining whether to subsidize mobile handsets from different vendors, or it could be to evaluate performance under realistic load and channel conditions which would be difficult to achieve at reasonable cost using cabled equipment.
Several different types of over-the-air testing exist. Some examples of the most common ones are described in the following paragraphs.